The use of fatty acid N-alkyl-polyhydroxyalkylamide, in particular of fatty acid N-methylglucamide, in detergents and cleaners is known from DE-A-4 430 085, DE-A-4 326 950, DE-A-4 432 366, DE-A-4 424 823, WO 92/06153, WO 92/06156, WO 92/06157, WO 92/06158, WO 92/06159 and WO 920/6160.
Essential advantages of the fatty acid N-alkyl-polyhydroxyalkylamides are their high cleaning power, their good biodegradability and the fact that they are prepared from renewable raw materials.
A disadvantage for the use and formulatability is a limited solubility in water of this class of surfactants, in particular from a chain length of C16 or more. At higher concentrations in water, fatty acid-N-alkyl-polyhydroxyalkylamides tend to form gels, or they form precipitates. Higher temperatures to reduce gel formation and viscosity lead to increased hydrolysis of the detersive substance.
WO 92/06160 describes preparations in the form of a paste which comprise fatty acid N-alkyl-polyhydroxyalkylamide and ethoxylated nonionic surfactants, in particular ethoxylated alkylphenols, ethoxylated primary and secondary aliphatic alcohols or ethoxylated alkylpolysaccharides.